1. Field of the Invention
This invention relates generally to signal reproducing systems that use light for reproducing information signals recorded on a recording medium, and more particularly is directed to improvements in reproducing systems, as aforesaid, in which a semiconductor diode laser device is used to supply the light for reproducing the recorded signals.
2. Description of the Prior Art
Systems have been proposed some for reading out information recorded mechanically or optically on the surface of a recording medium, for example, a disc or plate, by scanning the surface of the recording medium with light and detecting the reflection from the surface of the recording medium. In such systems, solid-state lasers, such as the ruby laser, or gas lasers, such as the He-Ne laser, have been employed as a light source to supply the light for scanning the recording medium. These lasers are relatively large and, therefore, the reproducing apparatus for such conventional systems become very large and have to be provided with many mirrors or prisms to guide the light to the recording medium from the laser with the intention of possibly minimizing the size of the apparatus. This results in an apparatus that is expensive and very complicated in addition to being large in size. Further, in the conventional systems the reflection from the surface of the recording medium is received by a light sensitive device to detect changes in intensity of the reflection so that the recorded signals are reproduced in response to the changes in intensity of the reflection. Accordingly, it is further required to provide a complicated and expensive optical system to obtain reproduced signals with a satisfactory S/N ratio.